The present invention is related to prosthetic heart valve replacement, and more particularly to devices, systems and methods for collapsing prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into the patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery. When the collapsed valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be effectively replaced by the prosthetic valve), the prosthetic valve can be released from the delivery apparatus and re-expanded to full operating size. Typically, in its full operating size, the prosthetic valve engages adjacent native tissue of the patient to firmly anchor itself in the patient.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. The stent functions as a frame to secure the valve structure. In order to deliver such a prosthetic heart valve into a tube-like delivery apparatus and ultimately the patient, the prosthetic heart valve must first be collapsed or crimped to reduce its diameter or annular perimeter. Some of the known methods and devices for accomplishing this are relatively simple. For example, it is well known in the art to use a funnel attached to a tube-like delivery apparatus to cause a gradual reduction in the diameter or annular perimeter of a stent. More complex devices, such as the one disclosed in U.S. Pat. No. 7,530,253, can also be utilized. The common goal of each of these devices and methods is to collapse the prosthetic heart valve to the smallest diameter needed (i.e., small enough to fit into the delivery tube of a delivery apparatus) without damaging the valve tissue on the stent.
Despite the various advancements and improvements that have been made to the crimping process and the overall prosthetic valve replacement process, such methods, devices, and systems suffer from similar shortcomings. Among others, valve tissue or the like is often pinched or caught within the cell openings of the stent or between the struts of the stent as the diameter or annular perimeter of the prosthetic heart valve (i.e., stent and valve tissue therein) is reduced. This phenomenon is best illustrated in FIG. 1, in which such a prosthetic heart valve 10 is illustrated in a collapsed condition. As shown, the prosthetic heart valve 10 includes valve tissue 20 attached to a stent 30. When the valve 10 is collapsed, valve tissue 20 becomes caught or pinched between the struts 31 of the stent 30 and/or within the cell openings 32 of the stent 30. The chance of damage to the tissue 20 as the prosthetic heart valve 10 is delivered to the implant site exponentially increases when this occurs. Furthermore, tissue caught within the openings can prevent the prosthetic heart valve from being reduced to the required or smallest possible diameter or annular perimeter.
Although known methods of heart valve crimping technology provide improvements over prior art systems, methods, and devices, there is a need for further improvements. Among others, the presently claimed invention addresses some of these shortcomings.